1. Field of the Invention
This invention relates to disk head assemblies for supporting read/write heads adjacent rotating disks in disk drives. More particularly, this invention relates to means for attaching load beam assemblies to a head stack assembly or arm.
2. Description of Related Art
In computer disk drives, electromagnetic heads for reading and writing magnetic disks are mounted on relatively delicate structures known as "load beam assemblies". A plurality of load beam assemblies are typically firmly mounted on a structure known as a "head stack assembly". A head stack assembly typically consists of a plurality of support arms disposed in line parallel to the common axis of the disks and all carried by a common carriage. A common type of head stack assembly is an "E" block, which refers to the general shape of the arms and carriage of the head stack assembly.
It has been a continuing objective of the disk drive industry to produce disk drives of increased storage capacity and decreased size. One approach to increasing the storage capacity of a "hard" disk drive is to increase the number of disks. However, as the number of disks increases, the physical height of the drive increases as well. To minimize or eliminate the increase in overall height of the disk drive, workers in the art are continually seeking to reduce the spacing between disks. However, the space between each pair of disks in a stack must be sufficient to accommodate two magnetic heads, a head stack assembly support arm, and two load beam assemblies on which the heads are mounted. Even for disk drives, with a single disk, disk drive designers prefer the lowest mass structure possible for the head arm assembly so that the head actuator may be reduced in size and power and increased in speed of response.
Commonly assigned U.S. Pat. No. 4,829,395 entitled "Improved Load Beam/Flexure Assembly for Close Clearance Mini-Composite and Mini-Monolithic Winchester Disk Drive", discloses an improved load beam and head stack mounting assembly. This improved structure achieves a significant reduction in disk-to-disk spacing over the prior art by replacing the customary multi-piece head stack assembly with a unitary assembly, and by utilizing a ball-staking technique to attach the load beam assemblies to the head stack assembly in lieu of the customary technique using miniature machine screws. Utilization of the ball-staking technique disclosed in U.S. Pat. No. 4,829,395 (incorporated herein by reference) results in disk drives which are smaller in size, structurally simpler, and less expensive to manufacture than previously known drives.
FIG. 1 depicts a prior art "E" block head stack assembly 1 and a number of attached load beam assemblies 2, as disclosed in U.S. Pat. No. 4,829,395. Each load beam assembly 2 includes an insert (or staking plate) 2a and a flexure 2b. Each load beam assembly further includes a slider 2c attached to the end of the flexure 2b. An electromagnetic read/write head 3 is affixed to the slider 2c. The disk head 3 reads data from, or writes data to, an associated rotating computer disk 4.
A hollow, cylindrical boss (or staking hub) 5 extends from one surface of the insert 2a of the load beam assembly 2. A corresponding staking hole 6 is located in each arm of the "E" block 1. The boss 5 of the load beam assembly is dimensioned to fit into the staking hole 6 located in the arm of the "E" block. To firmly fasten the load beam assembly 2 to the "E" block 1, the boss 5 is inserted into the staking hole 6 and a ball-staking tool is then inserted into the hole of the boss. The staking tool expands ("swages") the boss to create a very tight friction fit against the sides of the staking hole 6. To ensure such a tight fit, the length of the boss 5 must be such that sufficient contact exists between the outer portion of the boss 5 and the inner portion of the staking hole 6 so as to resist accidental removal or repositioning.
Generally, head stack assemblies contain up to 16 load beam assemblies which are staked, or swaged, in line. Each arm of the "E" block must be of a height sufficient to accommodate the length of two bosses 5 (one inserted into each end of a staking hole 6). By utilizing the ball-staking technique disclosed in U.S. Pat. No. 4,829,395, the spacing between adjacent disks may be reduced to approximately 0.16 inch in a typical disk drive.
Although ball-staking has a number of advantages over the prior art, other techniques could be used to attach a load beam assembly to a head stack assembly.
It is an object of this invention to permit a reduction in the disk-to-disk spacing of a disk drive when using ball-staked load beam assemblies attached to a head stack assembly, thereby allowing for a reduction in size of the disk drive.
It is another object of this invention to permit a reduction in the disk-to-disk spacing of a disk drive when using load beam assemblies attached to a head stack assembly by means other than ball-staking, thereby allowing for a reduction in size of the disk drive.
It is yet another object of this invention to reduce the mass and thickness of a head arm assembly, thereby allowing for an increase in access speed and a decrease in size, mass, and power required.